The resident pair of adult Harlequin Shrimp (Hymenocera picta) at the Tulamben Slopes dive site in Tulamben Bay in Bali, Indonesia.
This is a mated pair, with the female pictured at the top of the image with her egg protective plates down.
Tulamben Slopes is one of the premier muck diving sites in the world, featuring black sand slopes that are some of the richest in the world.